The worldwide demand for portable electronic devices in the past decade have had an enormous impact on the development of portable energy storage devices. Batteries in which lithium ions shuttle between a cathode and an anode have emerged as the power source of choice for the high performance rechargeable battery market. The thick metal plates of traditional batteries have given way to lithium ion cells, which are lighter and more compact. Although the materials in today's batteries differ from those of displaced technologies, the basic two-dimensional character and layer-by-layer construction of the cells remain.
The planar two dimensional construction leads to several drawbacks, for example, in terms of energy storage capacity relative to size. Drawbacks include slow transport of ions, particle agglomeration inside the cell, particle to particle contact resistance, and containment of the particles in a binder that prevents the particles from contributing effectively to electron storage capacity. To address these issues, the thickness of the electrodes can be minimized in conventional two-dimensional devices. However, reduction of the electrode thickness results in a lower fraction of electroactive material in a fixed volume, resulting in a lower cell capacity.